The present invention relates to a heads-up display for a vehicle, which indicates a frequency received by a radio receiver.
In general, a radio receiver for use in an automotive vehicle includes an automatic tuning mechanism which allows automatic switching of a received frequency from one frequency value to another in accordance with selection made by a driver or passenger, resulting pincipally in an increase in operability of the tuner during vehicle run. In view of operation made by the driver or passenger, the radio receiver is often arranged in the vicinity of the center of the vehicle as viewed in a cross direction thereof and below an instrument panel. In that event, a received frequency is digitally displayed on the front of the radio receiver.
On the other hand, there is known a heads-up display arrangement which includes a combiner disposed in a front window panel of the vehicle, and a projector disposed within the instrument panel for projecting different data such as a vehicle speed, an actual amount of fuel, etc. to the combiner. Accordingly, if the heads-up display arrangement is applied to display the received frequency of the radio receiver, the driver will have a minimum motion of his eyes because the combiner is in the driver's sight. For structure of the projector of the heads-up display arrangement, see JP-A 60-192912.
With the radio receiver having a digital display on the front thereof, when checking the received frequency, the driver is required to move his eyes from a position ahead of the vehicle to same in the vicinity of the center of the vehicle as viewed in the cross direction thereof and below the instrument panel, raising a problem of security during vehicle run.
On the other hand, with the heads-up display arrangement, the driver will have a minimum motion of his eyes as described above. However, in case of the radio receiver having an ordinary automatic tuning mechanism, the digital display is changed to show one frequency after another during switching of a frequency from one to another in accordance with selection made by the driver or passenger, and such quick and successive change in display may affect the driver's eyes.
By way of example, if the driver or passenger selects a FM radio station of 80.0 MHz when receiving a frequency of 75.2 MHz, the digital display of the received frequency is successively changed approximately every 0.2 second from 75.2 to 80.0 in such a manner as 75.2, 75.3, . . . , 79.9, 80.0. The driver perceives this change in display as a flicker, resulting in a decrease in visibility ahead of the vehicle.